Magnetic core unit



Feb. 27, 1968 Fig.

TAKAO HISANO MAGNETIC CORE UNIT Filed Nov. 7, 1966 INVENTOR. I Tau/(0.0 Hisa. n o

United States Patent 3,371,301 MAGNETIC CORE UNIT Takao Hisano, Yolrosuka-shi, Japan, assignor to TDK Electronics Company, Limited, Tokyo, Japan, a corporation of Japan Filed Nov. 7, 1966, Ser. No. 592,614 1 Claim. (Cl. 336-83) This invention relates to magnetic core units to be used for communication transformers and is an improvement of the invention .of a U.S. patent application No. 510,512, now Patent No. 3,332,049.

Except special ones, conventional magnetic cores of ferrite to be used for transformers for communication and induction coils are mostly pot type magnetic cores and internal iron or external iron type magnetic cores. In the pot type magnetic core, holes or slits are made in an upper disk or annular wall forming a component part of the core so that pull-out wires of coils wound :within the magnetic core may be pulled out through said holes or slits. In case such magnetic core is to be used for such transformer for communication machines as, for example, a differential transformer having many pull-out terminals, it will be necessary to make so many holes or slits for pulling out the respective pull-out wires. However, if such many holes or slits are made, the magnetic resistance of the magnetic core will increase and therefore it will be difficult to obtain favorable characteristics of the transformer. Ii the number of the holes or slits is therefore decreased so that a proper number of pull-out wires may be pulled out through each common hole or slit, the characteristics of the transformer will deteriorate due to a floating capacity or the like produced between the pull-out wires. On the other hand, the internal iron or external iron type magnetic core has a form adapted to be used for transformers for communication machines having many pull-out terminals as mentioned above. However, in such magnetic core, as the magnetic circuit includes only a part of the coil wound on the magnetic core, the leakage and coupling of magnetic fluxes will be likely to occur. Further, in such case, within the housing of the transformer, there will remain a considerable still available space except the volume occupied by the magnetic core coils and terminal plates. In view of the fact that the characteristics of the transformer depend on the volume of the magnetic core, it can not be said to be proper to leave such considerable available space within the housing and it is desirable for the transformer to well occupy the capacity of the housing.

In order to attain the above mentioned object, the invention of the US. patent application No. $10,512 has been already made. However, in such core units, there may occur a trouble that the coil bobbin body will be broken during the assembling operation. In order to prevent such trouble, the present invention has been made.

A principal object of the present invention is to provide a core unit wherein, as the upper part of a magnetic core is opened, a terminal plate can be set in said part and, even there are many pull-out wires, the terminals can be fitted without impairing the characteristics of the magnetic core.

Another object of the present invention is to provide a core unit in which a shielding effect is given without using a shielding case and, as no shielding case is used, the space factor is high.

A further object of the present invention is to provide a core unit in Which the assembly is easy and the break of the bobbin body during the assembling operation is little.

Another object of the present invention is to provide a core unit in which the lead wire of the coil and the conmeeting terminal rod provided in the bobbin body can be easily connected with each other. i

The present invention shall now be explained with reference to the accompanying drawings in which:

FIG. 1 is a plan view of a core;

FIG. 2 is a side view of the core;

FIG. 3 is a perspective view of the core;

FIG. 4 is a perspective view of a bobbin;

FIG. 5 is a perspective view of a plate spring;

FIG. 6 is a perspective view of a case;

FIGS. 7 to 12 show an assembling order;

FIG. 13 is a perspective view of another embodiment of the case;

FIG. 14 is a of the core unit.

FIGS. 1 to 3 illustrate a magnetic core made of ferrite. Said magnetic core is formed of two core pieces 1 and 1' jointed with each other on the surface AA so as to form a box having an opening in the upper part. A space 2 is formed in the box. A columnar part 3 is provided to project inward across said space 2 from the side wall 4 of each of the core pieces 1 and 1.

For this magnetic core is used a magnetic material of the composition shown in Table 1. That is to say, a magnetic material of a high magnetic permeability and high magnetic stability is obtained by using as a main element manganese oxide, zinc oxide or iron oxide, compounding and adding such impurities as SiO CaCO V 0 Bi O and CaO to it and passing them through a firing step under a partial pressure of less than 5% oxygen and then through an inert atmosphere in a cooling step above 1000 C.

perspective view of another embodiment TABLE 1 HSA:

Fe O mol percent 53.35 MnO do 26.4 ZnO d0 20.25 Si0 wt. percent 0.007 CaCO do 0.03 V 0 do 0.07 HSB:

Fe O mol percent 52.60 MnO do 27.40 ZnO do 20.00 SiO wt. percent 0.007 CaCO do 0.03 Bi O do 0.03 HSC:

Fe O mol percenL- 51.75 MnO do 22.50 ZnO do 25.75 SiO wt. percent 0.003 CaO do 0.02 Bi O do 0.04

FIG. 4 illustrates a bobbin made of synthetic resin. 5 is a bobbin body having a cylindrical hole 6 made in the center. 7 and 7' are flanges provided at the respective ends of the bobbin body 5. Said flanges 7 and 7' are semicylindrical in the lower parts and have respective terminal fixing bases 8 and 8 provided in parallel with each other in the horizontal direction in the upper parts. A plurality of connecting terminal rods 9 and 9 are vertically erected on the upper surfaces of the above mentioned respective terminal fixing bases 8 and 8'. A slope is made toward the upper surface of the bobbin body 5 from the inside of the base part of each of said connecting terminal rods 9 and 9'. Side walls 10 and 10' are provided at both ends of the above mentioned respective terminal fixing bases 8 and 8.

FIG. 5 illustrates an arcuated plate spring 11 having slits '12 and 12' made in the widthwise direction near the respective ends.

FIG. 6 illustrates a case. 13 is a U-shaped case body having bent parts 14 and 14 bent inward at the respective ends. Said bent parts 14 and 14 are provided with respective inward projecting parts 15 and 15'. Further, extension parts 16 and 16 are provided on the respec tive side parts on one side of said case body 13. Legs 17 and 17 are formed by bending the respective extension parts 16 and 16 inward and then outward. Projections 18 and 18 are made on the respective extension parts 16 and 16.

The method of assembling the magnetic core unit of the present invention shall now be explained. In FIG. 7, the columnar parts 3 of the respective core pieces 1 and 1 are inserted into the cylindrical hole 6 of the bobbin body from both sides. This state is shown in FIG. 8. Now, the case body 13 is fitted in the direction indicated by the arrow X in FIG. 8. In such case, the fitting position of the case body 13 will be determined by the projections 18 and 18. This state is shown in FIG. 9. Then the lower end of the plate spring 11 is inserted between the core piece 1 and the end part of the case body 13, the projecting part 15 provided on the "case body 13 is fitted into the slit 12 in the lower part of the plate spring 11 (this state is shown in FIG. then the upper end of the case body 13 is slightly lifted upward, the upper part of the plate Spring 11 is put in between the piece and the upper end of the case body 13 (see FIG. 11) and the upper end of the case body 13 is returned to the original position so that the plate spring 11 may be inserted between the case body 13 and the piece and the core may be fixed to the case body 13. Thus it is easy to assemble the core unit of the present invention.

FIG. 13 illustrates another embodiment of the case body in which the projections 18 and 18 are made at the ends of the respective side walls. It is also possible to assemble the core unit as illustrated in FIG. 14.

While there has been described the preferred embodiment of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is aimed, therefore, to cover in the appended claim all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A magnetic core unit comprising:

a bobbin having a tubular bobbin body having a cylindrical hole made within it, flanges provided at the respective ends of said bobbin body, terminal fixing bases provided in parallel with each other in the horizontal direction in the upper parts of said respective flanges and a plurality of connecting terminal rods erected on the upper surfaces of said respective terminal fixing bases;

a core formed of two core pieces jointed with each other on the contact surface so as to form a box having an opening in the upper part, having a space within it and provided with a columnar part projecting inward across said space from the side wall of each of said core pieces, said columnar parts of the respective core pieces forming the core being inserted into the cylindrical hole of said bobbin body from both ends of said hole so that said core and bobbin may be integral to be an assembly;

a U-shaped case enclosing said assembly and having bent parts at the respective ends, projections provided on said respective bent parts and projecting parts provided to project inward for positioning; and

a plate spring inserted at both ends between the bent parts of the case and the core so that both ends of said plate spring engage with both ends of said case, said case being provided with a bent leg on each side wall.

No references cited.

LEWIS H. MYERS, Primary Examiner.

T. I. KOZMA, Assistant Examiner. 

1. A MAGNETIC CORE UNIT COMPRISING: A BOBBIN HAVING A TUBULAR BOBBIN BODY HAVING A CYLINDRICAL HOLE MADE WITHIN IT, FLANGES PROVIDED AT THE RESPECTIVE ENDS OF SAID BOBBIN BODY, TERMINAL FIXING BASES PROVIDED IN PARALLEL WITH EACH OTHER IN THE HORIZONTAL DIRECTION IN THE UPPER PARTS OF SAID RESPECTIVE FLANGES AND A PLURALITY OF CONNECTING TERMINAL RODS ERECTED ON THE UPPER SURFACES OF SAID RESPECTIVE TERMINAL FIXING BASES; A CORE FORMED OF TWO CORE PIECES JOINTED WITH EACH OTHER ON THE CONTACT SURFACE SO AS TO FORM A BOX HAVING AN OPENING IN THE UPPER PART, HAVING A SPACE WITHIN IT AND PROVIDED WITH A COLUMNAR PART PROJECTING INWARD ACROSS SAID SPACE FROM THE SIDE WALL OF EACH OF SAID CORE PIECES, SAID COLUMNAR PARTS OF 